JPH05175492A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To manufacture an inverse T type transistor with high reproducibility. CONSTITUTION:A groove 27 of a pattern of a gate electrode is formed in an SiO2 film 25, a polycrystalline Si film 24 and an SiO2 film 23, and a thinner SiO2 film 31 than the film 23 is formed in the bottom of the groove 27. Then, the groove 27 is buried with a polycrystalline Si film 32, the film 25 is removed, and a low concentration diffused layer 34 is formed. A sidewall made of the films 23, 24 and an SiO2 film 35 is formed on the side of the film 32, and a high concentration diffused layer 37 is formed. As a result, an inverse T type transistor having the films 32, 24 as gate electrodes, the films 32, 23 as gate insulating films and the layers 37, 34 as source.drain is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a method of manufacturing an inverse T-type transistor.

[0002]

2. Description of the Related Art As a transistor for relaxing a drain electric field and reducing a hot carrier effect, an LDD structure transistor has been conventionally known. However, in the LDD structure in which the sidewall of the gate electrode is formed of the insulating film and the sidewall is located on the low-concentration diffusion layer, the mutual conductance is higher than that of a normal transistor due to the hot carriers injected into the sidewall. On the contrary, it has been known to deteriorate early.

Therefore, in order to prevent such early deterioration of mutual conductance, a GOLD structure has been devised in which a gate electrode is overlapped with a low concentration diffusion layer.
However, this GOLD structure has a structural defect that the gate overlap capacitance is increased as compared with the LDD structure.

Therefore, as shown in FIG. 2, the gate electrode 11
Are overlapped on the low concentration diffusion layer 12, but the gate insulating film 14 on the low concentration diffusion layer 12 is made slightly thicker than the gate insulating film 13 on the channel region.
An inverse T-type transistor with a reduced gate overlap capacitance has been proposed (for example, Proceedings of the 51st Annual Meeting of the Society of Applied Physics, Autumn 1990, pp 575 26).
p-G-5 "Reduction of gate overlap capacitance of inverse T-type transistor").

[0005]

However, as is clear from the above-mentioned documents, the manufacturing method of the inverse T-type transistor has not been established yet, and it is only studied by simulation. Therefore, it is an object of the present invention to provide a method capable of manufacturing an inverse T-type transistor with good reproducibility.

[0006]

In a method of manufacturing a semiconductor device according to the present invention, a first insulating film, a first conductive film and a second insulating film are formed on a first conductivity type active region of a semiconductor substrate. The second insulating film, the first conductive film, and the first insulating film in the region where the gate electrode is to be formed are sequentially removed to form a groove, and the groove is formed at the bottom of the groove. A third insulating film thinner than the first insulating film is formed, and the second insulating film is removed after filling the groove portion with the second conductive film. The first diffusion layer,
The second conductive film is used as a mask to form in the active region, and a sidewall formed of the first insulating film, the first conductive film, and a fourth insulating film on the first conductive film is formed. A second diffusion layer of the second conductivity type, which is formed on the side surface of the second conductive film and has a relatively high impurity concentration, is formed in the active region by using the second conductive film and the sidewall as a mask. ..

[0007]

In the method of manufacturing a semiconductor device according to the present invention, the second
Forming a gate electrode with the conductive film of the second conductive film and the first conductive film contacting a part of the side surface of the second conductive film, and the third insulating film below the second conductive film and the first conductive film below the first conductive film. Forming a gate insulating film with the first insulating film, and forming the source / drain with the first diffusion layer having a low impurity concentration under the first insulating film and the second diffusion layer having a high impurity concentration outside thereof. Form. Since the first insulating film is thicker than the third insulating film, the gate insulating film on the first diffusion layer having a low impurity concentration is thicker than the gate insulating film on the channel region.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention applied to the manufacture of an inverse T-type transistor will be described below with reference to FIG.

In this embodiment, as shown in FIG.
The active region 22 is formed on the Si substrate 21 by a conventionally known method such as the OCOS method, and the surface of the active region 22 is thermally oxidized to form the SiO ₂ film 23 having a thickness of about 400 Å on this surface.

Then, a polycrystalline Si film 24 having a thickness of about 500Å and a SiO ₂ film 25 having a thickness of about 3000Å are CV
The entire surface is sequentially deposited by the D method. Then, the SiO ₂ film 2
The photoresist 26 is processed into a pattern of the gate electrode on 5.

Next, as shown in FIG. 1B, with the photoresist 26 as a mask, the SiO ₂ film 25 and the polycrystalline Si are formed.
The film 24 and the SiO ₂ film 23 are sequentially etched, and these films are removed to form the groove 27 of the pattern of the gate electrode.

After that, the photoresist 26 is removed, and the surface of the active region 22 exposed at the bottom of the groove 27 is thermally oxidized to form the SiO ₂ film 3 having a thickness of about 200Å at the bottom of the groove 27.
1 is formed. And, a polycrystalline S having a thickness of about 5000Å
The i film 32 is deposited on the entire surface by the CVD method, and the polycrystalline Si
Impurities are introduced into the film 32. Therefore, the polycrystalline Si film 32
And the polycrystalline Si film 24 contact each other on the inner surface of the groove 27.

Next, by etching back the entire surface of the polycrystalline Si film 32, only the groove 27 is formed in the polycrystalline Si film 3.
Fill with 2. Then, by etching the SiO ₂ film 25 with hydrofluoric acid, as shown in FIG.
The O ₂ film 25 is removed. As a result, the polycrystalline Si film 32 projects from the polycrystalline Si film 24.

After that, the polycrystalline Si film 24 and the SiO ₂ film 2 are formed.
Using the polycrystalline Si film 32 as a mask, an impurity 33 having a conductivity type opposite to that of the active region 22 is ion-implanted into the active region 22 at a low concentration with an energy that can pass through 3 and 3. As a result, the low concentration diffusion layer 34 is formed in the active region 22.

Next, the SiO ₂ film 3 having a thickness of about 2000Å
5 is deposited on the entire surface by the CVD method and the entire surface of the SiO ₂ film 35 is etched back, so that the side wall of the SiO ₂ film 35 is covered with the polycrystalline Si film 3 as shown in FIG.
It is formed on the side surface of 2.

Then, the polycrystalline Si film 24 and the SiO ₂ film 23 are etched by using the side wall made of the SiO ₂ film 35 as a mask. As a result, the SiO ₂ film 23 and the polycrystalline Si
The side wall composed of the film 24 and the SiO ₂ film 35 is made of polycrystalline Si.
It is formed on the side surface of the film 32.

After that, the polycrystalline Si film 32 and the SiO ₂ film 2 are formed.
3, the side wall composed of the polycrystalline Si film 24 and the SiO ₂ film 35 is used as a mask, and the impurity 3 having the same conductivity type as the impurity 33 is used.
6 is ion-implanted into the active region 22 at a high concentration. As a result, the high concentration diffusion layer 37 is formed in the active region 22.

In the above embodiment, the polycrystalline Si film 32,
An inverse T-type transistor having 24 as a gate electrode, SiO ₂ films 31 and 23 as a gate insulating film, and a high concentration diffusion layer 37 and a low concentration diffusion layer 34 as a source / drain was manufactured.

[0019]

In the method of manufacturing a semiconductor device according to the present invention, the gate insulating film on the first diffusion layer having a low impurity concentration is thicker than the gate insulating film on the channel region.
The inverse T-type transistor can be manufactured with good reproducibility.

[Brief description of drawings]

FIG. 1 is a side sectional view sequentially showing an embodiment of the present invention.

FIG. 2 is a schematic side sectional view of an inverse T-type transistor to which the present invention can be applied.

[Explanation of symbols]

21 Si substrate 22 Active region 23 SiO ₂ film 24 Polycrystalline Si film 25 SiO ₂ film 27 Groove portion 31 SiO ₂ film 32 Polycrystalline Si film 34 Low concentration diffusion layer 35 SiO ₂ film 37 High concentration diffusion layer

Claims (1)

[Claims] 1. A first insulating film, a first conductive film, and a second insulating film are sequentially stacked on an active region of the first conductivity type of a semiconductor substrate, and the gate electrode is formed in a region where the gate electrode is to be formed. A groove is formed by removing the second insulating film, the first conductive film, and the first insulating film, and a third insulating film thinner than the first insulating film is formed at the bottom of the groove. Then, after filling the groove portion with the second conductive film, the second insulating film is removed, and the second conductive type first diffusion layer having a relatively low impurity concentration is formed on the second conductive film. The side wall of the first conductive film, the first conductive film, and the fourth insulating film on the first conductive film is formed on the active region by using a mask as a side surface of the second conductive film. And forming a second diffusion layer of the second conductivity type having a relatively high impurity concentration by using the second conductive film and the sidewall as a mask. A method of manufacturing a semiconductor device formed in an active region.